clean-up libutils includes

moved Foo.h as first include of Foo.cpp, and
removed redundant includes.

Made NativeHandle non virtual.


Test: run & compile
Bug: n/a

Change-Id: I37fa746cd42c9ba23aba181f84cb6c619386406a
diff --git a/libutils/Unicode.cpp b/libutils/Unicode.cpp
index f1a41b9..5fd9155 100644
--- a/libutils/Unicode.cpp
+++ b/libutils/Unicode.cpp
@@ -16,11 +16,10 @@
 
 #define LOG_TAG "unicode"
 
+#include <utils/Unicode.h>
 #include <limits.h>
-#include <stddef.h>
 
 #include <log/log.h>
-#include <utils/Unicode.h>
 
 #if defined(_WIN32)
 # undef  nhtol